Optical imaging device, and lens control method and apparatus
The invention provides an optical imaging device, which includes: an input unit, adapted to receive lens category information that is inputted; a storage unit, adapted to store at least one lens control model; and a control unit, adapted to select, according to the lens category information that is inputted from the input unit, a corresponding lens control model from the storage unit, and to apply to a lens a control signal which control signal corresponds to a current status of the lens. The invention also provides a lens control method and apparatus. The optical imaging device of the invention can control and adjust various categories of lenses, thus effectively avoiding the problem of iris hunting.
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This application claims priority to Chinese Patent Application No. 200810144079.X filed Jul. 31, 2008, which is incorporated herein by reference as if reproduced in its entirety.
FIELD OF THE INVENTIONThe present invention relates to an optical imaging device, and a lens control method and apparatus.
BACKGROUND OF THE INVENTIONAn optical imaging device (e.g. a video camera, a digital camera, etc.) is typically equipped with a lens. In order to control the amount of light incident on the light sensitive surface inside the optical imaging device via the lens, an iris is mounted inside the lens. The extent to which the iris is opened or closed corresponds to a different amount of incoming light. In the existing optical imaging device, the extent to which the iris is opened or closed is determined by a control voltage provided from the imaging device to the iris.
For example, when in operation, the video camera calculates the brightness of each frame of image and compares the brightness with a target brightness value having been set to obtain a relative brightness value. The relative brightness value, which may be in the form of a ratio in dB, represents a difference between the current brightness level (Video level) and the target brightness value. Then, the control voltage of the iris is adjusted in real time according to an iris control model stored in advance in a storage unit of the video camera, so as to change the amount of incoming light of the iris. The so-called iris control model, as illustrated in
In another example, U.S. Pat. No. 5,739,854 discloses an apparatus being capable of adjusting in real time the amount of incoming light. In this apparatus, a detection unit is arranged to detect in real time the extent to which the iris is opened or closed, and to transport detected information to a circuit control unit; the circuit control unit performs certain processing for the information, and further transfers the processing result to an iris control unit; and the iris control unit adjusts the extent to which the iris is opened or closed according to an instruction of the circuit control unit. When there are multiple irises, a synchronization component is further arranged in the apparatus to synchronize control signals that are outputted from the iris control unit.
However, the iris control model stored in advance in the existing optical imaging device is set with respect to specific lens of the original manufacturer. In fact, lenses produced by different manufacturers may be different, and characteristics of their irises may also be different. Thus, the optical imaging device fails to be adaptive to those lenses of different categories, and is greatly limited in usage. For example, when a lens is replaced by that of a different category or that from a different manufacturer, due to the mismatch of the iris with the iris control model preset in the storage unit, a phenomenon that different irises respond at different rates to the same control voltage may occur, thus a problem of iris hunting may arise.
Furthermore, in the case that the curve of the iris control model is too steep, i.e. the control voltage offset corresponding to the relative brightness value is too large, the control voltage may also be large, thus the iris may be caused to act too fast. When the speed at which the iris acts exceeds the range that can be controlled by the optical imaging device, fast iris hunting may occur. As illustrated in
In the existing optical imaging device, there are similar problems in controlling other elements or performances of the lens, thus leading to limited categories of lenses being suitable to be mounted in the optical imaging device.
SUMMARY OF THE INVENTIONThe invention provides an optical imaging device, which includes: an input unit, adapted to receive lens category information that is inputted; a storage unit, adapted to store at least one lens control model; and a control unit, adapted to select, according to the lens category information that is inputted from the input unit, a corresponding lens control model from the storage unit, and to apply to a lens a control signal which control signal corresponds to a current status of the lens.
The invention further provides a lens control method, which includes: selecting, according to lens category information, a corresponding lens control model; and applying to, according to the lens control model, a lens a control signal which control signal corresponds to a current status of the lens.
The invention further provides a lens control apparatus, which includes: a storage unit, adapted to store at least one lens control model; a selection unit, adapted to select, according to lens category information, a corresponding lens control model from the storage unit, and to transfer a signal of the lens control model to an operation unit; and the operation unit, adapted to apply to, according to the lens control model, a lens a control signal which control signal corresponds to a current status of the lens.
Being compared with the prior art, the invention has advantages as follows:
The optical imaging device according to the invention includes a storage unit in which the lens control model is stored, lenses of different categories can be controlled and adjusted, and the problem of iris hunting is effectively avoided.
The lens control method according to the invention includes dynamic adjusting the lens control model, so that when a conventional shutter speed is used and exposure compensation is enabled, the various kinds of lenses can be adaptive to more implementation scenarios.
The lens control apparatus according to the invention includes an adjustment unit which adjusts several points being far away from the origin in the lens control model. This can avoid occurrence of too slow iris action around the convergence target, thus perfectly dealing with the contradiction between slow iris hunting and exposure compensation.
Referring to
Particularly, the input unit 340 is adapted to receive information inputted from the outside. In an embodiment, the information includes lens category information as well as outside inputted information.
The input unit 340 may be implemented in various manners. In an embodiment, the information may be received by way of a key, a switch, a jumper, etc. In another embodiment, the information may alternatively be inputted via an interface displayed on the body of the device. In a further embodiment, the information may alternatively be inputted using an On Screen Display (OSD). In a further embodiment, the information inputted by way of command lines from a remote log-in client may alternatively be received. In a further embodiment, the information may alternatively be inputted by remotely manipulating a Graphic User Interface (GUI).
The storage unit 320 is adapted to store at least one lens control model.
The storage unit 320 may be one or a combination of a flash memory, a Read Only Memory (ROM), a Random Access Memory (RAM), a Static Random Access Memory (SRAM), an Erasable Programmable Read Only Memory (EPROM) and an Electrically Erasable Programmable Read Only Memory (EEPROM).
The lens control model represents a relationship between a lens control signal and a lens status, thus the optical imaging device can apply a corresponding lens control signal to the lens according to the lens status.
In an embodiment, the lens control model may include an iris control model adapted to represent a relationship between an iris control signal and an iris status.
In an embodiment, the iris control model may particularly be an iris control voltage curve.
MIRISSCL×8=ΔVL(dB)×1024/6.02 (1)
As illustrated in
The iris control model may be not limited to the iris control voltage curve described above. In an embodiment, the iris control model may alternatively be an iris control current curve particularly adapted to represent a functional relationship between an iris control current and a current brightness value.
The lens 360 is adapted to obtain an image from the outside.
The image processing unit 330 is adapted to perform further processing for the image signal obtained by the lens 360.
The output unit 350 is adapted to implement an output of the optical imaging device.
The control unit 310 is adapted to select a corresponding lens control model from the storage unit 320 according to the lens category information that is outputted by the input unit 340, and to apply to the lens 360 a control signal which control signal corresponds to the current status of the lens. In an embodiment, the control unit 310 may control the extent to which the iris contained in the lens is opened or closed.
In a specific implementation, the control signal provided from the control unit 310 can be applied to the lens 360 after being processed by a lens control circuit (referring to
In an embodiment, the control signal provided from the control unit 310 includes a digital signal of the voltage offset, and a stop reference signal. As illustrated in
In another embodiment, as illustrated in
In a further embodiment, as illustrated in
The operation principle of the lens control circuit is analyzed in detail hereinbelow with the lens control circuit illustrated in
VIRIS
In the equation (2), G1, G2 and G3 respectively denote gains of the circuit for each of the signals when in the steady state. As analyzed in the above, when G1, G2, G3 and the stop reference voltage V1 are fixed, the control voltage VIRIS
More particularly, the lens control circuit illustrated in
|Ga|·|Gb|·|Gc|≧1 Condition 1
a+b+c=2nπ (n is an integer) Condition 2
Therefore, in an embodiment, the gain Ga of the amplifier 503 may be decreased to break the oscillation condition, so that no self-excited oscillation occurs in the circuit. In another embodiment, the gain Gc of the amplifier 505 may be decreased to break the oscillation condition, so that no self-excited oscillation occurs in the circuit. In a further embodiment, a capacitance inside the amplifier 505 may be modified (i.e. c is changed) to maintain the original frequency characteristics of the amplifier 505, so that no self-excited oscillation occurs in the circuit.
Referring to
The lens control model represents a relationship between a lens control signal and a lens status, thus the optical imaging device can apply a corresponding lens control signal to the lens according to the lens status.
In an embodiment, the lens control model may include an iris control model adapted to represent a relationship between an iris control signal and an iris status.
Lens control models may be classified in various ways. For example, they can be classified by categories or manufacturers of the lenses. In an embodiment, as illustrated in
In a specific implementation, the lens category information may be a lens category that is inputted by a user himself, or alternatively may be a lens category that is recognized by the optical imaging device in an automatic detection manner.
The corresponding lens control model can be selected in various ways. In an embodiment, it may be selected by way of software programming, for example, by way of using a Single Chip Micyoco, a Micro Control Unit (MCU) or a Field Programmable Gate Array (FPGA) to run a program, etc. In another embodiment, the lens control model may be selected by way of a specific hardware circuit. Particularly, the specific hardware circuit may be a multiple selection unit, a comparator, a control unit circuit, etc. In a further embodiment, the lens control model may be selected by way of a combination of software and hardware.
According to the lens control model, when the control signal corresponding to the current status of the lens is applied to the lens, the control signal can be generated from the control information contained in the lens control model, where the control information may be any information for controlling the lens, such as the offset of the control voltage, the value of the control voltage, the value of the control current, etc.
The control signal may be generated by way of various types of hardware circuit, software programming, or combination of software and hardware.
In a specific implementation, the control signal can be applied to the lens after being processed by the lens control circuit. In an embodiment, as illustrated in
In another embodiment, the lens control circuit particularly includes digital-to-analog conversion units 501 and 502, and amplifiers 503 and 505. The digital-to-analog conversion unit 501 is adapted to convert the digital signal of the stop reference signal into an analog signal, and the digital-to-analog conversion unit 502 is adapted to convert the digital signal of the voltage offset into an analog signal. The amplifier 503 is adapted to perform operation amplification for the analog values of the stop reference signal and the voltage offset signal, and to output the control voltage to adjust the lens 360. The lens 360 outputs in real time a voltage feedback signal, and the amplifier 505 amplifies the feedback signal and then feeds it back to the voltage offset signal input end of the amplifier 503. Using the circuit structure having a negative feedback can more accurately adjust the control voltage outputted from the amplifier 503, thus to effectively control the lens 360.
In a further embodiment, as illustrated in
In a further embodiment, the control signal of the lens can be adjusted according to the lens control model by way of software programming, for example, by way of using a Single Chip Micyoco, a Micro Control Unit (MCU) or a Field Programmable Gate Array (FPGA) to run a program, etc.
In a further embodiment, the control signal of the lens can be adjusted according to the lens control model by way of a combination of software and hardware. For example, the digital signals can be inputted by way of software programming, and the other signal amplification circuits can be implemented by way of a hardware circuit.
Taking the lens control circuit illustrated in
VIRIS
In the equation (3), VDAC
The lens control method of the above embodiment can be used to control various elements or performances of the lens, e.g. the above lens control method may be used to control the iris.
In an embodiment, the iris control method includes: selecting, according to lens category information, a corresponding iris control model; and applying to, according to the iris control model, an iris a control signal which control signal corresponds to a current status of the lens.
Specifically, various iris control models corresponding to different categories of lens are configured in the optical imaging device. When in operation, the optical imaging device selects a corresponding iris control model according to the category of the mounted lens, and controls the iris to open or close according to the selected iris control model.
Particularly, the iris control model represents a relationship between an iris control signal and an iris status. For example, it can be represented as the iris control voltage curve illustrated in
When in operation, the optical imaging device calculates the brightness of each frame of image and compares the brightness with the target brightness value having been set to obtain the relative brightness value, and then adjusts in real time the control voltage of the iris according to the selected iris control model to change the amount of incoming light of the iris.
In another embodiment, the iris control method further includes dynamically adjusting the iris control model described above. The dynamical adjustment refers to adjusting the currently-selected iris control model according to a setting of shutter speed and of exposure, so as to meet the convergence requirement of a general scenario and also to avoid occurrence of fast iris hunting to the maximum.
Exposure compensation can control the amount of exposure at any time, i.e. change the convergence target of the iris in the lens. The amount of exposure is determined by the luminance of environment, the light transmittance of the lens system, the shutter speed and the light transmittance of the iris, where the light transmittance of the iris can be represented by the equation (4):
Particularly, r denotes the radius of the currently-opened light transmission area of the iris, and R denotes the radius of the light transmission area when the iris being totally open. When a exposure compensation of −2 EV or even −3 EV is utilized in the environment having an extremely high luminance, if the conventional shutter speed of 1/30˜ 1/100 second is still used, then in order to control the amount of incoming light to be at a very low level, the iris may be in an ultimate state of almost being totally closed, i.e. 0<r<<R. In the ultimate state, even a very small action of the iris can result in a very large relative brightness value, thus may trigger a control voltage far away from the origin in the lens control model. If the curve is steep, there is a great possibility that the current brightness level (Video Level) may be continuously pushed back and forth by the large control voltage, i.e. fast iris hunting occurs.
In order to avoid iris hunting, in an environment having an extremely high luminance (e.g. shooting against the burning sun), when the conventional shutter speed is used and an exposure compensation below −2 EV is utilized, a flat lens control model curve shall be arranged. However, when the lens control model curve is too flat, i.e. the voltage offset is too small, not only the action of the iris in the lens is slowed down, but also two cases may occur: (1) when the convergence action of the iris in the lens is almost finished, i.e. the current brightness level (Video Level) is close to the convergence target, the voltage offset may be small, thus the iris may already stop its action before the current brightness level reaches the preset target; and (2) if the convergence action of the iris is from closing to opening, when case (1) occurs, the current brightness level keeps below the preset target, and when such an offset is beyond the range that can be tolerated by the lens control circuit and lasts for several seconds, the optical imaging device may determine that “the iris is already totally open, but the current brightness level has not reach the target yet”. Then, the optical imaging device forces the lens to open totally, and this may result in the image to become bright all in a sudden and may cause convergence again. In some brighter circumstances, the inertia of the iris action may render the current brightness level to fall back to be below the preset target again, and at this time, there may be an endless loop and the slow iris hunting may appear.
Referring to
Particularly, the storage unit 1101 is adapted to store at least one lens control model; the selection unit 1103 is adapted to select, according to lens category information, a corresponding lens control model from the storage unit 1101, and to transfer a signal of the lens control model to an operation unit 1105; and the operation unit 1105 is adapted to apply to, according to the lens control model, a lens a control signal which control signal corresponds to a current status of the lens.
The lens control apparatus may vary in various ways. For example, referring to
Particularly, the storage unit 1201 is adapted to store at least one lens control model; the selection unit 1203 is adapted to select, according to lens category information, a corresponding lens control model from the storage unit 1201, and to transfer a signal of the lens control model to an operation unit 1205; the adjustment unit 1207 is adapted to dynamically adjusting the lens control model, and to transfer an adjustment signal to the operation unit 1205; and the operation unit 1205 is adapted to apply to, according to information provided in the lens control model and the adjustment signal of the lens control model outputted from the adjustment unit 1207, a lens a control signal which control signal corresponds to a current status of the lens.
For another example with reference to
Particularly, the storage unit 1301 is adapted to store at least one lens control model; the selection unit 1303 is adapted to select, according to lens category information, a corresponding lens control model from the storage unit 1301, and to transfer a signal of the lens control model to an operation unit 1305; the operation unit 1305 is adapted to apply to, according to the lens control model, a lens a control signal which control signal corresponds to a current status of the lens, and to output the control signal to the adjustment unit 1307; and the adjustment unit 1307 is adapted to adjust, according to the control signal received from the operation unit 1305, the lens control model stored in the storage unit 1301.
The lens control apparatus as illustrated in
In another embodiment, the lens control apparatus can alternatively be implemented in a digital video camera apparatus having a DVI, or HDMI interface.
In a further embodiment, the lens control apparatus can alternatively be implemented in an IP video camera apparatus having an Ethernet interface.
In a further embodiment, the lens control apparatus can alternatively be implemented in a video camera apparatus having a Wireless Lan, WiFi, WIMAX, or Bluetooth wireless communication interface.
In a further embodiment, the lens control apparatus can alternatively be implemented in a video camera apparatus having a USB interface.
In a further embodiment, the lens control apparatus can alternatively be implemented in a video camera apparatus having an IEEE 1394 interface.
The lens control apparatus as illustrated
The lens control apparatus as illustrated
Although the invention has been described in the above with the preferred embodiments, the invention is not limited to those. Any skilled in the art can make various alterations and modifications without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is defined by the appended claims.
Claims
1. An optical imaging device, comprising:
- an input unit, adapted to receive lens category information that is inputted;
- a storage unit, adapted to store at least one lens control model;
- a control unit, adapted to select, according to the lens category information that is inputted from the input unit, a corresponding lens control model from the storage unit, and to apply to a lens a control signal which control signal corresponds to a current status of the lens; and
- a lens control circuit adapted to convert the control signal provided from the control unit into a control voltage used for controlling the lens,
- wherein the control signal comprises a voltage offset and a stop reference signal, and the lens control circuit comprises: a first digital-to-analog conversion unit, adapted to convert a digital signal of the stop reference signal into an analog signal; a second digital-to-analog conversion unit, adapted to convert a digital signal of the voltage offset into an analog signal; and a first amplifier, adapted to perform operation amplification for the analog values of the stop reference signal and the voltage offset signal, and to output the control voltage.
2. The optical imaging device according to claim 1, wherein the lens control circuit further comprises:
- a second amplifier, adapted to feed a voltage feedback signal that is output from the lens back to a voltage offset signal input end of the first amplifier.
3. The optical imaging device according to claim 1, wherein the lens control model comprises an iris control model adapted to represent a relationship between an iris control signal and an iris status.
4. The optical imaging device according to claim 3, wherein the iris control model is an iris control voltage curve.
5. A lens control method, comprising:
- selecting, according to lens category information, a corresponding lens control model;
- applying to, according to the lens control model, a lens a control signal which control signal corresponds to a current status of the lens; and
- adjusting, according to a setting of shutter speed and of exposure, the currently-selected lens control model.
6. The lens control method according to claim 5, wherein the lens category information is at least one of a lens category that is inputted from outside and a lens category that is recognized in an automatic detection manner.
7. The lens control method according to claim 5, wherein the lens control model comprises an iris control model adapted to represent a relationship between an iris control signal and an iris status.
8. The lens control method according to claim 7, wherein the iris control model is an iris control voltage curve.
9. The lens control method according to claim 5, wherein the adjusting the lens control model comprises:
- selecting an adjustment mode which adjustment mode corresponds to information of the setting of shutter speed and of exposure; and
- updating the lens control model according to the selected mode.
10. A lens control apparatus, comprising:
- a storage unit, adapted to store at least one lens control model;
- a selection unit, adapted to select, according to lens category information, a corresponding lens control model from the storage unit, and to transfer a signal of the lens control model to an operation unit;
- the operation unit, adapted to apply to, according to the lens control model, a lens a control signal which control signal corresponds to a current status of the lens; and
- an adjustment unit, adapted to dynamically adjust the lens control model, and to transfer an adjustment signal to the operation unit.
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Type: Grant
Filed: Jul 28, 2009
Date of Patent: May 1, 2012
Patent Publication Number: 20100026828
Assignee: Sony Corporation (Tokyo)
Inventors: Junrong Guo (Pudong District), Xiaobo Zhou (Pudong District)
Primary Examiner: John Villecco
Attorney: Oblon, Spivak, McClelland, Maier & Neustadt, L.L.P.
Application Number: 12/510,636
International Classification: H04N 5/225 (20060101); H04N 5/235 (20060101); G03B 17/00 (20060101);